The present invention relates to electronic data processing and more particularly to methods and means for maximizing the rate of printing by electronic printers by varying the printing rate as a function of the print density of data being received from a remote source.
Printing systems exist today that have the capability of responding to data from a source at the normal printing speed of the printer. Oftentimes because of electronic and mechanical limitations associated with the printing process, these printing systems are designed to operate well within the worst case situation. Such arrangements do not distinguish between variations of the print density of data being received from the source. It would be desirable if the printing function could be carried out substantially always at the maximum printing rate consistent with the power and mechanical limits associated with the printer design.
A particular application for such a system exists in the case of the line printer wherein a full line of input data characters are stored in memory then processed sequentially before a plurality of such stored input data characters are printed along a line on a record medium. In such an arrangement it would be desirable to control the number of characters printed simultaneously during any one alignment of print characters, which do the printing, along a line on a record medium. It is also desirable to limit the maximum rate at which the print characters are caused to effect printing over a period of time corresponding to a plurality of such alignments.
One prior art approach detects a droop in the power supply voltage and inhibits line feed for a predetermined duration. Using the droop in a power supply is not a sufficiently precise method for effecting close control. Also it is desirable to delay printing to varying degrees depending on the degree of variations in print rate.
Protection also is provided against an excessive average print rate by inhibiting line feed for a predetermined time after the line is printed. However, for certain data this approach would result in excessive delay and therefore provide less than the maximum tolerable print rate.
Accordingly, one object of the invention is to provide an improved apparatus for controlling the printing of a printing system so that it operates at a maximum rate within the power and mechanical limitations of the system design.
Another object of this invention is to provide a method and apparatus for maximizing the printing speed of an electronic printer despite variations in the patterns of incoming data.
Another object of this invention is to suspend printing of input data character signals whenever the number of such signals available for printing exceed a predetermined number during any single alignment of print characters along a line on a record medium.
Another object of this invention is to provide a method and apparatus for suspending printing of input data character signals whenever the number of such signals available for printing exceeds a predetermined average rate.
Another object of this invention is to protect a printer from overstress due to an excessive number of columns of symbols or characters being printed substantially simultaneously, while preventing loss of data due to the protecting scheme.
Another object of this invention is to protect a printer from overstress due to an excessive print rate, while insuring that printing take place substantially at no less than an acceptable maximum average rate, even though the data pattern has considerable variation.
Another object of this invention is to provide an improved data printing method and arrangement for a printer having design limitations.
In accordance with one embodiment of the invention, an arrangement is provided wherein a plurality of recording characters are adapted for effective serial movement across each line in succession on a record medium containing column locations and a plurality of such characters are available for substantially simultaneous recording along each line. To control recording, means are provided for sensing the number of such characters to be substantially simultaneously recorded during each columnar alignment of said characters to provide a control signal when said number reaches a limit N, where N represents less than the maximum number of aligned characters which could be printed during such alignment, and means responsive to said control signal to limit recording of characters within each such alignment to a number which is a function of the value of N.
Further recording control is provided by means which sense the number of such characters to be recorded during a given plurality of columnar alignments of said characters to provide a control signal when said number reaches a limit M, where M represents less than the maximum number of aligned characters which could be recorded during such given plurality of columnar alignments, and means responsive to said control signal to limit recording of characters within such given plurality of alignments to a number which is a function of the value of M. In a particular embodiment, said given plurality of alignments corresponds to a given plurality of lines, and the means responsive to said control signal limits recording of characters beyond the completion of the character recording on the line associated with the providing of said control signal.